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Trick equipotential bonding

I’m faced with a really tricky one and I might have to walk away.

went to an EVSE quote today and it’s a classic case of oh dear they built over the top of it! So the property has an external gas meter, 10mm bond at the meter but the metallic gas pipe then goes under ground (paved drive) before entering the house after the point at which it is bonded. Indoors the whole place is tiled or laminate floors, there must be a T in the gas pipe somewhere under there because it appears straight out a wall behind the cooker and weirdly down from the ceiling above the boiler. Getting a bond over to either is not something that is likely to be acceptable to the client. I remember reading a code of practice a nice plumber/gas safe engineer showed me once that stated that where the meter is external and the customer side of the service goes underground again before entering the property that the bond should ideally be located internally 600mm from its reemergence rather than within 600mm of the meter.

personally I’ve always preferred an internal bond with external meters, mostly because I’ve found so many corroded ones outside, but…As it’s not practical to do that without destroying a newly tiled floor to run the cable under, can I say that this is not ideal but is still compliant as there is an external bond within 600mm of the meter, all be it before an earth potential is reintroduced? I’m not entirely sure it would have the desired effect as it is.

They’ve also had their earth electrode paved over, which begs the question why budding young builders on the city and guilds don’t get better training on some basic electrical awareness, in fact considering how laughably easy the PartP exam is, surely it’s more appropriate for other trades to do it than sparkies? Because let’s face it, it’s not us going around paving over earth pins or boxing in the stopcock now is it?

rant over

  • One of my customers had a buried pipe similar to this and the gas supply company dug a trench up her garden, then extended the main in yellow plastic and relocated the meter.

  • However in this instance the consumers pipework runs under the drive, so is extraneous but must surely be wrapped in something to avoid corrosion?

    I'm not clear what the situation is - it could be either a meter box on the outside of the house and the pipework had originally been surface mounted for a distance on the outside wall and then been covered by later driveway resurfacing, or whether it comes from a separate structure (e.g. brick built meter housing near the boundary) and then runs underground for some distance to the house. If the latter I'd expect the underground section to be in yellow PE pipe, at least if vaguely modern. If the former I'd suspect a complete lack of Denso tape - but the pipe to be in copper and so fairly resistant to corrosion anyway (unlike the old black iron gas pipes).

       - Andy.

  • Are the yellow mains gas pipes only plastic on the outer? With a corrugated steel lining? I'm sure I've seen some like that.